Japan Orders Nuclear Plant Operators to Obtain More Generators

Radiation readings spiked sharply in one reactor at the stricken Fukushima Daiichi nuclear plant after a powerful aftershock late Thursday, according to data released by the government, a development that might indicate new damage to the already compromised reactor.

But the plant owner, the Tokyo Electric Power Company, said the gauge used to measure radiation was most likely broken.

The high radiation was measured in the drywell of Reactor No. 1, directly below the reactor pressure vessel and part of the primary containment that is a crucial barrier preventing the escape of radioactive materials. The drywell reading raised the worrisome possibility that highly radioactive water had escaped, and perhaps even material from the nuclear core, although this was far less likely.